The invention relates to a sensor device for determining the layer thickness of a thin layer of an electrically conducting or semiconducting material.
Such sensor devices are used if, for example, in the chemical-mechanical processing of a silicon wafer, the thickness of a copper film on the wafer has to be ascertained. The corresponding layers may in this case have a thickness of the order of magnitude of μm or less.
Measuring methods involving contact which can be used to ascertain layer thicknesses are known from the prior art. These include, for example, the eddy current method according to DIN EN ISO 2360, ASTM B244, the magneto-inductive method according to DIN EN ISO 2178, ASTM B499 and the magnetic method according to DIN EN ISO 2178. Ascertainment of the layer thickness by determining the electrical resistance of the layer is also a measuring method involving contact.